lock.h revision 1.11
1/* $NetBSD: lock.h,v 1.11 2007/02/19 23:35:49 he Exp $ */ 2 3/*- 4 * Copyright (c) 2000, 2001 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Jason R. Thorpe. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39/* 40 * Machine-dependent spin lock operations. 41 * 42 * NOTE: The SWP insn used here is available only on ARM architecture 43 * version 3 and later (as well as 2a). What we are going to do is 44 * expect that the kernel will trap and emulate the insn. That will 45 * be slow, but give us the atomicity that we need. 46 */ 47 48#ifndef _ARM_LOCK_H_ 49#define _ARM_LOCK_H_ 50 51#include <arm/cpufunc.h> 52 53#define mb_read drain_writebuf /* in cpufunc.h */ 54#define mb_write drain_writebuf /* in cpufunc.h */ 55#define mb_memory drain_writebuf /* in cpufunc.h */ 56 57static __inline int 58__swp(int __val, volatile int *__ptr) 59{ 60 61 __asm volatile("swp %0, %1, [%2]" 62 : "=r" (__val) : "r" (__val), "r" (__ptr) : "memory"); 63 return __val; 64} 65 66static __inline void __attribute__((__unused__)) 67__cpu_simple_lock_init(__cpu_simple_lock_t *alp) 68{ 69 70 *alp = __SIMPLELOCK_UNLOCKED; 71} 72 73static __inline void __attribute__((__unused__)) 74__cpu_simple_lock(__cpu_simple_lock_t *alp) 75{ 76 77 while (__swp(__SIMPLELOCK_LOCKED, alp) != __SIMPLELOCK_UNLOCKED) 78 continue; 79} 80 81static __inline int __attribute__((__unused__)) 82__cpu_simple_lock_try(__cpu_simple_lock_t *alp) 83{ 84 85 return (__swp(__SIMPLELOCK_LOCKED, alp) == __SIMPLELOCK_UNLOCKED); 86} 87 88static __inline void __attribute__((__unused__)) 89__cpu_simple_unlock(__cpu_simple_lock_t *alp) 90{ 91 92 *alp = __SIMPLELOCK_UNLOCKED; 93} 94 95#endif /* _ARM_LOCK_H_ */ 96